mirror of https://github.com/ArduPilot/ardupilot
107 lines
3.5 KiB
Markdown
107 lines
3.5 KiB
Markdown
# Logger Notes
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## Format Types
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The format type specifies the amount of storage required for the entry
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and how the content should be interpreted.
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| Char | C Type |
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|------|--------|
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|a | int16_t[32]|
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|b | int8_t|
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|B | uint8_t|
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|h | int16_t|
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|H | uint16_t|
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|i | int32_t|
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|I | uint32_t|
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|f | float|
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|d | double|
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|n | char[4]|
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|N | char[16]|
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|Z | char[64]|
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|L | int32_t latitude/longitude (so -35.1332423 becomes -351332423)|
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|M | uint8_t flight mode|
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|q | int64_t|
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|Q | uint64_t|
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Legacy field types - do not use. These have been replaced by using the base C type and an appropriate multiplier column entry.
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| Char | CType+Mult |
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|------|--------------|
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| c | int16_t * 100|
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| C | uint16_t * 100|
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| e | int32_t * 100|
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| E | uint32_t * 100|
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## Units
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All units here should be base units.
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This means battery capacity uses "amp \* second" not "milliAmp \* hours".
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Please keep the names consistent with Tools/autotest/param_metadata/param.py:33
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| Char | Unit Abbrev. | Description | Notes |
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|-----|---|---|---|
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| '-' | "" | no units e.g. Pi or a string |
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| '?' | "UNKNOWN" | Units which haven't been worked out yet....|
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| 'A' | "A" | Ampere|
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| 'd' | "deg" | of the angular variety | -180 to 180|
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| 'b' | "B" | bytes|
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| 'B' | "B/s" | bytes per second |
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| 'k' | "deg/s" | degrees per second | Not an SI unit, but in some situations more user-friendly than radians per second|
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| 'D' | "deglatitude" | degrees of latitude|
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| 'e' | "deg/s/s" | degrees per second per second | Not an SI unit, but in some situations more user-friendly than radians per second^2|
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| 'E' | "rad/s" | radians per second|
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| 'G' | "Gauss" | Gauss | Not an SI unit, but 1 tesla = 10000 gauss so a simple replacement is not possible here|
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| 'h' | "degheading" | 0.? to 359.?|
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| 'i' | "A.s" | Ampere second|
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| 'J' | "W.s" | Joule (Watt second)|
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| 'l' | "l" | litres|
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| 'L' | "rad/s/s" | radians per second per second|
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| 'm' | "m" | metres|
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| 'n' | "m/s" | metres per second|
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| 'N' | "N" | Newton|
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| 'o' | "m/s/s" | metres per second per second|
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| 'O' | "degC" | degrees Celsius | Not an SI unit, but Kelvin is too cumbersome for most users|
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| '%' | "%" | percent|
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| 'S' | "satellites" | number of satellites|
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| 's' | "s" | seconds|
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| 'q' | "rpm" | revolutions per minute| Not an SI unit, but sometimes more intuitive than Hertz|
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| 'r' | "rad" | radians|
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| 'U' | "deglongitude" | degrees of longitude|
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| 'u' | "ppm" | pulses per minute|
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| 'v' | "V" | Volt|
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| 'P' | "Pa" | Pascal|
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| 'w' | "Ohm" | Ohm|
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| 'W' | "W" | watt |
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| 'X' | "W.h" | watt hour |
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| 'Y' | "us" | pulse width modulation in microseconds|
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| 'z' | "Hz" | Hertz|
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| '#' | "instance" | (e.g.)Sensor instance number|
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## Multipliers
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This multiplier information applies to the raw value present in the
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log. Any adjustment implied by the format field (e.g. the "centi"
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in "centidegrees" is *IGNORED* for the purposes of scaling.
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Essentially "format" simply tells you the C-type, and format-type h
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(int16_t) is equivalent to format-type c (int16_t*100)
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tl;dr a GCS shouldn't/mustn't infer any scaling from the unit name
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| Char | Multiplier | Description |
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|------|------------|---|
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| '-' | 0 | no multiplier e.g. char[4] |
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| '?' | 1 | multipliers which haven't been worked out yet |
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| '2' | 1e2 ||
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| '1' | 1e1 ||
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| '0' | 1e0 | x1 |
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| 'A' | 1e-1 ||
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| 'B' | 1e-2 ||
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| 'C' | 1e-3 ||
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| 'D' | 1e-4 ||
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| 'E' | 1e-5 ||
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| 'F' | 1e-6 ||
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| 'G' | 1e-7 ||
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| 'I' | 1e-9 ||
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| '!' | 3.6 | (milliampere \* hour => ampere \* second) and (km/h => m/s)|
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| '/' | 3600 | (ampere \* hour => ampere \* second)|
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